Working Wth Objects

[Recaip Sanli]

this.x needs to be different than x so this.x-x isn't 0. I do not understand why this code keep giving me result of 0?


Class

   public double distance(int x, int y){
      double newX = Math.pow(this.x - x, 2);
      double newY = Math.pow(this.y - y, 2);
      return Math.sqrt(newX + newY);
   }
   
   public double distance(MyPoint Object){
      double newX = Math.pow(this.x - x, 2);
      double newY = Math.pow(this.y - y, 2);
      return Math.sqrt(newX + newY);
   }

Main

MyPoint[] points = { p1, p2, new MyPoint(7, 3) };
		for (int i = 0; i < points.length - 1; i++)
		{
			System.out.print("The distance from " + points[i].toString());
			System.out.print(" to " + points[i + 1].toString() + " is: ");
			dis = points[i].distance(points[i + 1]);
			System.out.println(dis);
		}

[Recaip Sanli]

In the line 6, points[i] print one pair of x,y and points[i + 1] print another pair. All I need to do is to send those two pairs to the class, perform a math calculation and calculate the area.

[Paul Clapham]

   public double distance(MyPoint Object){
      double newX = Math.pow(this.x - x, 2);
      double newY = Math.pow(this.y - y, 2);
      return Math.sqrt(newX + newY);
   }

This method completely ignores the input parameter. Looks like you copied it from the other distance() method but then forgot to make the necessary changes to use the x and y values from the MyPoint object passed into the method.

[Recaip Sanli]

That's exactly where I am stuck! I do not know how I can deal with the objects that are sent into the methods. How do I work with x-y values of the object sent in?

[Recaip Sanli]

Found it, thank you for the hint!!

  public double distance(MyPoint Object){
     MyPoint o = (MyPoint) Object;
     double newX = Math.pow(this.x - o.x, 2);
     double newY = Math.pow(this.y - o.y, 2);
     return Math.sqrt(newX + newY);
  }

[Campbell Ritchie]

Don't use Math.pow(x, 2); use x * x.
Don't mess around with square roots or similar when there is a method in the Math class which will do all that work for you.

[Junilu Lacar]

Don't do this.

   public double distance(MyPoint Object){
      MyPoint o = (MyPoint) Object;

It's confusing and unnecessary.

In the first line, Object is taken as the parameter name. That's confusing because Object is also a standard class name in Java. Avoid using standard class names for any of your own identifiers.
In the second line, you cast the parameter which is already declared as a reference to a MyPoint to MyPoint. There's no point to doing that, it's totally unnecessary.

This does the same thing:

public double distance(MyPoint point) {
    double newX = this.x - point.x;
    double newY = this.y - point.y;
    return Math.sqrt(newX * newX + newY * newY);
}

Better yet, think of better names for newX and newY. Those names don't reflect what they represent, which are the distances between the current point and the other point on the X and Y axes, respectively. A better way to write it would be:

public double distance(MyPoint point) {
    double dX = this.x - point.x;
    double dY = this.y - point.y;
    return Math.sqrt(dX * dX + dY * dY);
}

// or spell it out
public double distance(MyPoint point) {
    double distanceX = this.x - point.x;
    double distanceY = this.y - point.y;
    return Math.sqrt(distanceX * distanceX + distanceY * distanceY);
}